-- Discussion containing changed information from previous version are highlighted. --
235
FXUS63 KGLD 291715
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
1115 AM MDT Wed May 29 2024

.KEY MESSAGES...

- Chance for severe weather and flooding throughout the week.
  Confidence in specific hazards change each day, but a very
  active pattern is expected.

- Potential for critical fire weather conditions Sunday and
  into early next week. High temperatures could also climb into
  the 90`s.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 358 AM MDT Wed May 29 2024

Light south/southeasterly winds this morning along with ample
moisture left from the storms yesterday will make a favorable
environment for patchy to locally dense fog to form across most of
the CWA this morning. This fog is expected to lift by the mid-
morning.

SPC has continues the Slight risk for severe thunderstorms on
Wednesday and Thursday. Through Saturday, there is concern of
flooding across the CWA. The Hydrology section below will go into
more detail about this risk.

Today, the upper-level ridge axis looks to be moving over the CWA
and will exit to the east throughout the evening and overnight
hours. A 250 mb trough will be moving in from the northwestern CONUS
and push the ridge on to the east. A 500 mb shortwave expected to
form around 21-0Z this afternoon, move east over the CWA, and
continue impacting the CWA until about 12Z Thursday. Around mid-day
today. a high pressure system over the Gulf of Mexico will extend a
ridge up into the easter Great Plains, leading to a persistent LLJ
that will move additional moisture into the mid-CONUS. These
features will fuel the storms during the short-term. The Slight risk
for severe weather is focused over eastern Colorado and adjacent
counties to the east. The main threats with these storms will be 1-
1.5 inch hail and wind gusts near 60 MPH. A brief tornado cannot be
ruled out early in the event, mainly in the southwestern CWA. As the
evening progresses into the night, the severe potential will drop
significantly, but showers and storms are expected to continue into
the eastern portions of the CWA into Thursday morning.

CAMs are generally in agreement with the timing and storm mode with
convection later today. Storms look to form around the Palmer Divide
around 21Z and by 0Z the storms will be at our western borders.
Initially, storms will develop as individual cells along the
north/south oriented dry line. By 0Z, the cells will have grow more
numerous into a long line of storms, potentially reaching all the
way into Canada. Soon after, the line will break up and clusters of
cells will move across the region. CAMs are suggesting we will have
two clusters moving through the CWA. One will move to the east-
northeast from Yuma county while the other will move east-southeast
and remain generally south of I-70. Confidence in these exact
locations is only about 50% as the CAMs have been struggling with
the past few events.

Thursday, the upper-level trough works farther to the east, as does
the ridge. The LLJ looks to remain consistent until Thursday night,
mainly due to the 850 mb ridge either strengthening or splitting off
and becoming it`s own high pressure system near the Great Lakes
region. Thursday night, an 850 mb lee low is expected to move to the
south of the CWA around 6-12Z Friday. While this will disrupt the
LLJ moving moisture directly into the for the remainder of the
period, the low will cause wrap around moisture to move into the
area. This moist conveyor belt will keep PWATS in the 1-1.3+ inch
range through the period.

Thursday is looking to have the highest PWATS, ranging from 1.15-1.4
inches, EBWD shear around 25-35 kts, and the 0C line being around
14,000 feet. These parameters suggest storms that form will produce
heavy rain and potentially severe weather. Instability in the
environment could easily turn heavy rain storms into large hail
storms. MUCAPE from the RAP and NAM is around 3,000 J/kg. The most
likely hazards Thursday will be heavy rain leading to flooding,
hail, and strong winds, in that order.

Temperatures will be in the mid 70s to low 80s today while tomorrow
will be a bit cooler, with majority of the CWA remaining in the 70s.
Low temperatures will remain fairly warm Wednesday night through
Saturday night due to generally southerly winds and cloud cover, and
will remain in the 50s to low 60s Wednesday night with Thursday
night seeing upper 40s and mid 50s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 205 AM MDT Wed May 29 2024

For the weekend and into next week, active weather is forecast with
continued daily chances for storms and severe weather. Next week is
beginning to look like we`ll see some of our hottest temperatures of
the season so far in the 90`s.

For Friday and Saturday, the area looks to be in a inbetween pattern
with zonal flow on the back side of an upper trough. With this,
temperatures are forecast to generally be in the 70`s and 80`s. A
mix of clouds and afternoon/evening storm chances remain in the
forecast as available moisture over the area is forecast to remain
relatively high. Severe storms will likely be possible both days,
but could be fairly limited or marginal as the forecast lack of
synoptic forcing will likely limit storms to forming off the higher
terrain in Colorado and moving east.

For Sunday and the beginning of next week, the overall trend in
guidance favors some ridging, but some smaller waves moving through
the flow may keep us more zonal. As such, near to above average
temperatures in the 80`s and 90`s are forecast along with continued
daily chances for storms. That being said, chances are a bit lower
compared to this current week as drier air may be able to move into
the area if the flow takes on more of a southwesterly direction or
if the ridging amplifies. This could shift storm chances more to the
east where moisture would more likely remain available. May need to
keep an eye out for critical fire conditions on Sunday as a smaller
wave moves through and when temperatures are currently forecast to
be into the 90`s.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
-- Changed Discussion --
Issued at 1115 AM MDT Wed May 29 2024

KGLD...VFR conditions are expected from taf issuance through 01z
then again after about 16z. Southerly winds gusting to 35kts are
expected from taf issuance through 01z. From 01z-07z, the
terminal could be impacted from showers and thunderstorms with
gusty winds, perhaps some hail and locally heavy rainfall that
could produce sub VFR visibilities. From 08z-16z, southerly
winds gusting to around 20kts will subside while slowly veering
to the southwest. Stratus and fog are anticipated, producing sub
VFR conditions. After 17z, VFR conditions return with winds from
the north around 10kts.

KMCK...VFR conditions are expected from taf issuance through at
least 09z. Southeast winds gusting to 30kts are expected from
taf issuance through 02z, decreasing to around 10kts through
08z. There is a chance for showers and thunderstorms to impact
the terminal from 03z-08z. After 09z, stratus and fog will
develop, creating sub VFR cigs/vis with winds from the southeast
under 10kts.
-- End Changed Discussion --

&&

.HYDROLOGY...
Issued at 358 AM MDT Wed May 29 2024

Highly efficient moisture return has already began and will continue
into the end of the workweek with aid from the 850 mb LLJ. This
moist conveyor belt will cause PWATS to increase above 1 inch
starting Wednesday and potentially remain that way until Sunday. The
highest values will be in the eastern CWA, but the majority of the
Tri-State area will have a good chance (70%+) at seeing PWATS above
1 inch. Throughout this active pattern, a high melting layer is also
expected, generally 11,000-15,000 feet agl.

Tuesday evening saw 2-3+ inches of rain in Cheyenne county Colorado,
and a few other locations in eastern Colorado. This rain did not
cause any flooding, but it will make it easier for flooding to occur
over the next few days. Locations that received heavy rainfall are
not fully primed for flooding (SAC-SMA soil saturation is around 30-
45% in these area), but will become susceptible to flooding sooner
than normal.

Based on what the CAMs are showing, the southern cluster of storms
would be a slower mover and larger in size, meaning based on its
projected path (south of I-70 across the CWA) and potential for
heavy rainfall, it will need to be watched closely for flash
flooding.

Thursday is currently the best day for training storms to create
heavy rainfall that could lead to rate-driven flash flooding and
duration-driven areal flooding. Friday and Saturday are also at risk
for flooding potential due to a combination of efficient rain
producing storms and potentially multiple days of heavy rain
saturating the soil.

Current confidence in localized flooding occurring through Saturday
is around 25-45%. Confidence in widespread flooding is about
20%.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.

&&

$$

SHORT TERM...CA
LONG TERM...KAK
AVIATION...99
HYDROLOGY...